Transcript Python for Series 60

Python for Series 60
(i.e. Python on a Phone)
Jukka Laurila
EuroPython 2005
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What is Series 60?
• 100-220 MHz ARM processor (and a separate
processor for telephony functions)
• Typically 4 – 8 MB of free RAM
• FAT formatted Flash as mass storage
• Symbian OS
• Series 60 software for UI, comms, applications etc.
• GSM, GPRS, UMTS, Bluetooth, IrDA, WLAN...
• Display: 176x208 12-18 bpp LCD panel (currently,
N90 has 352x416)
• Integrated camera (usually)
• 20 million shipped by Nokia alone
• In other words: A pretty capable computer
• ...with an always-on Internet connection
• ...that’s with you all the time
• ...that you can write your own software for
• ...IF you spend enough effort
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Why port Python to a phone?
• Symbian C++ development is slow and hard
• Java has limited access to platform capabilities
• Easy to learn, clear syntax
• High productivity (See: Lutz Prechelt: An empirical comparison of seven
programming languages, IEEE Computer 33(10):23-29, October 2000)
• Extending and embedding easy and efficient
• Popular
• Good standard library
• Reasonable memory footprint
• Ports to other “embedded” systems already existed at the time (PalmOS)
• Other choices:
• ECMAScript
• Perl (actually we did port Perl, too)
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Past and Future
• Stable 1.0 release Dec 2004
• 1.1.x pre-alpha series releases ongoing, soliciting feedback from external
developers
• We need you!
• Stable 1.2 release coming later this year
• A standard component in future phones? Maybe.
• Source release? Working on it...
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Python for Series 60 1.1.5
• Python 2.2.2 as a Symbian DLL
• Extensible and embeddable with the Python/C API
• Standard library
• socket (TCP/IP, SSL, Bluetooth serial connections), urllib, httplib,
nntplib, thread, math, re, sre, marshal, anydbm, whichdbm etc...
• File system access
• Many modules written in Python work unchanged or with minor changes
• C modules need to be modified
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Bindings to Series 60 API’s
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appuifw: a simple S60 UI API
SMS sending
Native Symbian SQL database (e32db module), dbm (over e32db)
Location API (Cell ID)
Background “daemon” process support
New in 1.1 series:
• 2D graphics
• Binding to Symbian GDI graphics
• API partly similar to PIL
• Image loading, saving, scaling, rotation, bitblit
• Set of graphics primitives
• Raw key event handling
• camera
• contacts
• calendar
• telephony
• audio: record and play samples, MIDI
• sysinfo
• miscellaneous improvements, like rich text support
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appuifw
• Our own API for Series 60 GUI programming
• S60 UI made as simple as possible
• Just one widget allowed on screen at a time
import appuifw
appuifw.note(u’Hello World!’)
Form
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Listbox & Tabs Text widget Content handler Popup menu
EuroPython_PythonForSeries60.PPT / 2005-06-27 / Jukka Laurila
Multifield query
Porting difficulties…
• No global writable data allowed in DLL’s
• Globals moved to heap-allocated struct referenced via TLS
• No standard C++ exceptions
• Instead TRAP/Leave (think setjmp/longjmp), Cleanup Stack
• Memory and disk space constraints
• We can run out of memory at any time and should survive it
• C stdlib not quite complete
• Locale-specific float formatting: 3.14 vs. 3,14
• Symbian and S60 API complexity
• Active Objects: co-op multitasking and event handling the Symbian way
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Co-op multitasking and event handling the
Symbian way
Active Object: object that inherits from CActive, has a RunL method
 think “event handler” or “co-operative task”
Active Scheduler: a loop that runs RunL methods of AO’s in sequence
 think “event loop” or “co-operative multitasking engine”
Thread
AS
AO
RunL() { ...run code... run nested AS ...run more code... }
AO
RunL() { ...refresh UI widget... }
AO
RunL() { ...put data received from a socket to a buffer...}
lock=e32.Ao_lock()
lock.wait()
e32.ao_yield()
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start a nested AS and run until the lock is .signal()ed
start a nested AS and run through it once
EuroPython_PythonForSeries60.PPT / 2005-06-27 / Jukka Laurila
Remaining problems
• unicode vs. str ugliness:
appuifw.note(u’foo’)
appuifw.popup_menu([u’first’,u’second],u’Pick one:’)
• Very little performance optimizations have been done yet, so there’s a lot of
room for improvement
• Slow imports
• Globals access using Thread Local Storage is a real killer
• Native Symbian resources aren’t threadsafe… at all.
• No gc support yet
• Unfreed native resources cause an error message on exit
• …which is nasty since reference cycles are easy to make
• Creating C extensions on Symbian is not as easy as it should be
• Manual work required, no distutils, SWIG, SIP or any of that magic (yet)
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Demos!
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Questions?
For more information:
http://www.forum.nokia.com/
http://discussion.forum.nokia.com/
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